こちらから最新版取得
$ tar zxvf php-4.3.2.tar.gz
$ cd php-4.3.2
$ ./configure ?-enable-trans-sid ?-with-apxs2=/usr/local/apache2/bin/apxs ?-enable-mbstring ?-with-mysql=/usr/local/mysql ?-with-zlib
$ make
$ su
# make install
# cp php.ini-dist /usr/local/lib/php.ini

/usr/local/apache2/conf/httpd.confの編集
LoadModule php4_module modules/libphp4.so
AddType application/x-httpd-php .php .html

/usr/local/lib/php.iniの編集
doc_root=”/usr/local/apache2/htdocs”
extension_dir=”/usr/local/lib/php/extensions”
include_path=”.:/usr/local/include/php:/usr/local/lib/php”

Ａｐａｃｈｅ再起動
/usr/local/apache2/bin/apachectl restart

/usr/local/apache2/htdocs/test.phpの編集
<?php phpinfo(); ?>

http://localhost/test.phpが表示されるか確認。